Image Sensor and Image Sensor Integrated Type Active Matrix Type Display Device

ABSTRACT

To fabricate an active matrix type display device integrated with an image sensor at a low cost and without complicating process, an image sensor laminated with TFT and a light receiving unit is formed on a light receiving matrix, a display matrix is arranged with TFT and pixel electrodes on a matrix and formed with an electrode layer functioning as a black matrix, a lower electrode of the light receiving unit is formed by a starting film the same as that of the black matrix, a terminal for fixing potential of an upper electrode is formed by starting films the same as those of a signal line, the electrode layer or pixel electrodes and the terminals function also as shield electrodes for a side face of the light receiving unit since potential thereof is fixed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image sensor having a lightreceiving unit for converting light into electric charge and a scanningcircuit for scanning light receiving pixels and reading electric chargegenerated at the light receiving unit as signal, particularly to animage sensor of a laminated layer type in which a light receiving unitis laminated on a scanning circuit.

Further, the present invention relates to an active matrix type displaydevice integrated with an image sensor and a display matrix of alaminated layer type.

2. Description of Related Art

An optical sensor is widely used as a sensor for converting light intoelectric signal. For example, an optical sensor is widely used as animage sensor for a facsimile, a copier, a video camera, a digital stillcamera or the like.

To meet request of multimedia, high density formation of pixels of animage sensor has been rapidly progressed. For example, in respect ofstandard of pixels of a digital still camera, the high speed formationis promoted from VGA (Video Graphics Array) (640×480=310,000 pixels) toSVGA (Super VGA) or XGA (Extended Video Graphics Array), further to SXGA(Super XGA) (1280×1024=1,310,000 pixels).

Further, to meet request of small-sized formation and low cost formationof a multimedia tool such as a digital still camera or the like, anoptical system has been downsized year by year from ⅔ inch to ½ inch, ⅓inch and ¼ inch.

In this way, an image sensor which is a small light receiving cellhaving excellent conversion efficiency has been requested to realizehigh density formation of pixels and small-sized formation of an opticalsystem. To satisfy the request, for example, to promote an apertureratio, there has been proposed an image sensor of a laminated layer typein which a scanning circuit for reading electric charge generated at alight receiving unit as signal and the light receiving unit (photo diodeunit) are laminated.

In recent years, a technology of fabricating TFT (Thin Film Transistor)using polycrystal silicon which is referred to as polysilicon TFT hasbeen studied intensively. As a result, it becomes possible to fabricatea drive circuit of a shift register circuit or the like by a polysiliconTFT and there has been reduced into practice a liquid crystal panel ofan active matrix type in which a display matrix and a peripheral drivecircuit for driving the display matrix are integrated on the samesubstrate. Thereby, low cost formation, small-sized formation andlight-weighted formation of a liquid crystal panel have been achievedand therefore, the liquid crystal panel has been used in display unitsof various information devices and portable devices of a personalcomputer, a portable telephone, a video camera, a digital camera and soon.

There has been currently reduced into practice a small-sized portableinformation processing terminal device which is more excellent than anotebook type personal computer in portability, inexpensive and of apocket size and an active matrix type liquid crystal panel is used for adisplay unit thereof. According to such an information processingterminal device, data can be inputted from the display unit by a touchpen system, in order to input data/graphic information on paper or imageinformation, a peripheral device of a scanner, a digital camera or thelike is needed. Therefore, the portability of the information processingterminal device is deteriorated. Further, economic burden is imposed ona user to purchase the peripheral device.

Further, an active matrix type display device is also used in a displayunit for a TV conference system, a TV telephone, a terminal for internetor the like. According to the system or the terminal, a camera fortaking picture of a dialogue partner or a user is provided and a displayunit and a camera unit are individually fabricated into modules.

SUMMARY OF THE INVENTION

It is a problem of the present invention to achieve further promotion ofan aperture rate in an image sensor of a laminated layer type andparticularly, the present invention relates to a structure of a lead-outterminal for fixing an upper electrode on a light incident side of alight receiving unit to constant potential.

It is an object of the present invention to resolve the problemsmentioned above and to provide an active matrix type display devicewhich is made intelligent to be provided with both of picture takingfunction and display function by installing an image sensor on asubstrate formed with a display matrix and peripheral circuits.

In order to resolve the above-described problem, according to an aspectof the present invention, there is provided an image sensor laminatedwith a light receiving unit for converting light into electric charge ata light receiving pixel region in which a plurality of light receivingpixels are arranged and a signal reading unit for reading electriccharge generated at the light receiving unit as a signal, the lightreceiving unit comprising:

a plurality of lower electrodes separated from each other at respectivesof the light receiving pixels, a photoelectric conversion layer, and anupper electrode common to the light receiving pixels, the image sensorfurther comprising:

a lead-out terminal formed at a layer different from a layer of theupper electrode;

the upper electrode is connected to the lead-out terminal on a lightincident side at outside of the light receiving pixel region.

Further, according to another aspect of the present invention, there isprovided an image sensor integrated type active matrix type displaydevice which is an active matrix type display device comprising on asame substrate:

a display matrix having a plurality of pixel electrodes in which aplurality of select lines and a plurality of signal lines are arrangedin a shape of a lattice, and an image sensor laminated with a lightreceiving unit for converting light into electric charge and a signalreading unit for reading the electric charge generated at the lightreceiving unit as a signal in a light receiving pixel region in which aplurality of light receiving pixels are arranged;

wherein the light receiving unit includes a plurality of lowerelectrodes separated from each other at respectives of the lightreceiving pixels, a photoelectric conversion layer and an upperelectrode common to the light receiving pixels, the upper electrode isconnected to a lead-out terminal on a light incident side, and thelead-out terminal is formed at a layer different from a layer of theupper electrode.

Further, in the image sensor integrated type active matrix type displaydevice mentioned above, an electrode layer covering at least the signallines and the select lines is formed and the lower electrode of thelight receiving unit is formed by a starting film the same as a startingfilm of the electrode layer.

Further, in the image sensor integrated type active matrix type displaydevice, the pixel matrix comprises active devices formed on thesubstrate and connected to the sinal lines and the select lines, a firstinsulating film covering the active devices, an electrode layer formedon the first insulating film and covering at least the signal lines andthe select lines, a second insulating film formed on the electrodelayer, and pixel electrodes formed on the second insulating film andconnected to the active devices,

wherein the image sensor comprises the signal reading unit formed on thesubstrate, the first insulating film covering the signal reading unit, aplurality of the lower electrodes formed on the first insulating film,comprising a starting film the same as a starting film of the electrodelayer and separated from each other at respectives of the lightreceiving pixels, a photoelectric conversion layer formed on the lowerelectrodes, an upper electrode formed on the photoelectric conversionlayer and common to the light receiving pixels, the second insulatingfilm covering the upper electrode, and a lead-out terminal formed on thesecond insulating film and connected to the upper electrode, and

wherein the upper electrode is formed by a starting film the same as astarting film of the pixel electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a liquid crystal panel according toEmbodiment 1;

FIG. 2 is a front view of the liquid crystal panel according toEmbodiment 1;

FIGS. 3A, 3B and 3C are sectional views for explaining fabrication stepsof the liquid crystal panel according to Embodiment 1;

FIGS. 4A and 4B are sectional views for explaining fabrication steps ofthe liquid crystal panel according to Embodiment 1;

FIG. 5 is a front view for explaining fabrication steps of lightreceiving matrix according to Embodiment 1;

FIG. 6 is a front view for explaining fabrication steps of the lightreceiving matrix according to Embodiment 1;

FIGS. 7A and 7B are a front view and a sectional view for explainingfabrication steps of the light receiving matrix according to Embodiment1;

FIGS. 8A and 8B are a front view and a sectional view for explainingfabrication steps of the light receiving matrix according to Embodiment1;

FIG. 9 is a front view for explaining fabrication steps of a displaymatrix according to Embodiment 1;

FIG. 10 is a front view for explaining fabrication steps of the displaymatrix according to Embodiment 1;

FIG. 11 is a front view for explaining fabrication steps of the displaymatrix according to Embodiment 1;

FIG. 12 is a front view for explaining fabrication steps of the displaymatrix according to Embodiment 1;

FIG. 13 is a front view for explaining fabrication steps of a drivecircuit according to Embodiment 1;

FIG. 14 is a front view for explaining fabrication steps of the drivecircuit according to Embodiment 1;

FIG. 15 is a sectional view of a liquid crystal panel according toEmbodiment 2;

FIG. 16 is a sectional view of a liquid crystal panel according toEmbodiment 3; and

FIGS. 17A, 17B and 17C are schematic outlook views of products to whichliquid crystal panels of Embodiment 6 are applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An explanation will be given of a display device integrally providedwith an image sensor on an element substrate in an active matrix typedisplay device of a peripheral circuit integrated type according to anembodiment in reference to FIG. 1.

A light receiving matrix 111 and a display matrix 121 are formed on asubstrate 500. Signal lines 307 and select lines 302 are arranged in alattice shape at the display matrix 121 and an active element comprisingTFT connected with the signal line 307 and the select line 302 isarranged in the lattice for each display pixel.

The display matrix 121 is arranged with a first insulating layer 540covering TFT and an electrode layer 308 formed on the first insulatinglayer 540 and covering at least the select lines 302 and the signallines 307. Although in FIG. 1, the electrode layer 308 is illustrated tobe divided to disconnect, the electrode layer 308 is integrally arrangedin a lattice shape.

A second insulating film 550 is formed on the electrode layer 308 andpixel electrodes 312 are formed on the second insulating film 550. Thepixel electrode 312 is connected to TFT of the display matrix via acontact hole provided to the first and the second insulating films 540and 550.

The electrode layer 308 prevents light from being incident on the activeelement arranged in the display matrix 121, makes light from aneffective display region to contribute to display and prevents displaycharacteristic from deteriorating. Further, by fixing potential of theelectrode layer 308, a variation of potential at the select line 302 orthe signal line 306 can be prevented from being fed back to potential ofthe pixel electrode 312.

Meanwhile, the light receiving matrix 111 is arranged with a scanningcircuit for scanning light receiving pixels by using TFTs as switchingelements as a signal reading unit. The signal reading unit is coveredwith the first insulating film 540 similar to the active element in thedisplay unit. A light receiving unit is formed on the first insulatinglayer 540. Electric charge generated at the light receiving unit or achange in potential of the light receiving unit is read as a signal by asecond insulating gate type semiconductor device.

The light receiving unit is constituted by a plurality of lowerelectrodes 208 which are separated from each other for respective lightreceiving pixels, a photoelectric conversion layer 210 formed over thelower electrodes 208 and an upper electrode 212 formed over thephotoelectric conversion layer 210 and common to the light receivingpixel. The lower electrode 208 is formed by a starting film the same asthat of the electrode layer 308. The light receiving unit is passivatedby the second insulating film 550.

The photoelectric conversion film 210 may use a silicon-basesemiconductor of amorphous silicon, amorphous silicon germanium or thelike which is intrinsic or substantially intrinsic. A silicon-basesemiconductor film having pin junctions may be used. Further, when thelight receiving unit is rendered a photoconductor, a ZnSe/ZnCdTe film ora laminated film of Se/Te/As which is generally used in a solid imagetube may be used.

Further, in FIG. 1, a film 209 and a film 211 are n-type and p-typeamorphous silicon films for coupling the photoelectric conversion layer210 comprising amorphous silicon with the lower electrode 208 and theupper electrode 212 in ohmic coupling. Further, in place of the n-typeamorphous silicon film 209, a film functioning as a barrier film of theamorphous silicon film 210 may be provided. In this case, a siliconoxide film, a silicon nitride film, a silicon carbide film or the likeadded with an n-type impurity of phosphorus or the like can be used.

In order to fix potential of the upper electrode 212, at outside of thelight receiving matrix 111, the upper electrode 212 of the lightreceiving unit is connected to a lead-out wiring 606 comprising astarting film the same as that of the pixel electrode 312 via a contacthole provided in the second insulating film 550.

Further, the lead-out wiring 606 is connected to a lead-out terminal 603comprising a starting film the same as that of the electrode layer 308and the lead-out terminal 603 is connected to a lead-out terminal 601comprising a starting film the same as that of the signal line 307. Thelead-out terminal 601 is connected an outer terminal constituting aconnecting portion for connecting with a wiring outside of the substratedirectly or via other wiring. By fixing the lead-out terminal 601 atconstant voltage, the potential of the upper electrode 212 can be fixedconstant.

In the laminated layer type image sensor, all of opening portions arecovered by the upper electrode 212, the potential is fixed constant andaccordingly, noise invading from a light incident side can be shieldedby the upper electrode 212. Further, according to the embodiment, theside face of the light receiving unit is surrounded by the terminals601, 603 and 606 and potential of the terminals is fixed constant andaccordingly, noise from the side face of the light receiving unit canalso be prevented from invading. Therefore, the S/N (Signal/Noise) ratiocan be promoted and an image sensor with high function and highreliability can be provided.

The embodiment is characterized in that the display matrix 121 and thelight receiving matrix 111 are formed on the same substrate andaccordingly, the film forming process and the patterning process aremade common in the respective matrices 111 and 121. The insulating films540 and 550 are commonly provided to the respective matrices 111 and121.

Further, the electrode layer 308 and the lower electrode 208 and thepixel electrode 312 and the lead-out terminal 606 are formed by the samefilm forming processes and patterning processes. Thereby, there can beprovided an active matrix type display device of an image sensorintegrated type by minimizing additional steps by which the fabricationcost can be restrained inexpensively.

Further, the embodiment is characterized in that in order to fix thepotential of the upper electrode 212 the lead-out terminal 606 forconnecting the upper electrode 212 to an external terminal, is notintegrally formed with the upper electrode 212. The characteristicresides in that the lead-out terminal 606 is formed at a layer differentfrom that of the upper electrode 212 and is connected on the lightincident side of the upper electrode 212.

When the lead-out terminal 606 is formed integrally with the upperelectrode 212, patterns of the upper electrode 212 and the photoelectricconversion layer 210 are different from each other and patterning stepsof the upper electrode 212 are different from those of the photoelectricconversion layer 210. Therefore, the aperture ratio may be deterioratedby a shift of masks in patterning of the upper electrode 212.

On the other hand, by constituting the upper electrode 212 and thelead-out terminal by conductive films arranged at layers different fromeach other, there is achieved an effect in which patternings of theupper electrode 212 and the photoelectric conversion layer 210 cancontinuously be carried out by using a single one of a resist mask andthe aperture ratio is prevented from deteriorating by the shift ofmasks. Further, when the photoelectric conversion layer 210 ispatterned, damage caused in the patterning process of the photoelectricconversion layer 210 can be restrained since the upper electrode 212 ispresent on the photoelectric conversion layer 210.

According to the embodiment, the upper electrode 212 and the lead-outterminal 606 are constituted by conductive films arranged at layersdifferent from each other. In order to pattern the upper electrode 212and the photoelectric conversion layer 210 by the same process, it isalso important that the conductive layer is formed above the upperelectrode 212 and the lead-out terminal 606 is connected to the lightincident side of the upper electrode 212. Further, by forming thelead-out terminal 606 by a process the same as that of the pixelelectrode 312, consistency with fabrication process of an active typedisplay device is established.

Embodiments

A detailed explanation will be given of embodiments of the presentinvention in reference to FIG. 1 through FIG. 17.

Embodiment 1

The embodiment relates to a transmission type liquid crystal displaydevice in which an image sensor and a display matrix are provided on thesame substrate.

FIG. 2 is a front view of a liquid crystal display device according tothe embodiment. As shown by FIG. 2, both of a light receiving region 110and a display region 120 are provided on a substrate 100. The lightreceiving region 110 is formed with the light receiving matrix 111 inwhich a plurality of light receiving pixels are arranged in a matrixshape, peripheral circuits 112 connected to the light receiving matrix111 and a terminal unit 113 in which lead-out terminals are arranged tosurround portions of the periphery of the light receiving matrix 111 towhich the peripheral circuits are not connected. The light receivingmatrix 111 is provided with a structure in which a light receiving unit(photodiode) and semiconductor devices for reading electric chargegenerated at the light receiving unit as signals, are laminated.

Meanwhile, the display region 120 is installed with the display matrix121 in which pixel electrodes and active elements which are connected tothe pixel electrodes are arranged and peripheral drive circuits 122 fordriving the active devices arranged at the display matrix 121. Further,an outside lead-out terminal unit 130 constituting a connecting portionfor connecting with a wiring of a power source line or the like outsideof the substrate, is provided on the substrate 100.

According to the embodiment, insulating gate type semiconductor devicesof the light receiving matrix 111, active elements of the display matrix121 and semiconductor devices arranged at the peripheral drive circuits112 and 122, are simultaneously fabricated by TFTs (Thin FilmTransistors) by using CMOS (Complementary Metal Oxide Semiconductor)technology. An explanation will be given of a method of fabricating aliquid crystal panel according to the embodiment as follows.

FIGS. 3A, 3B and 3C and FIGS. 4A and 4B show sectional views of thelight receiving matrix 111, the lead-out terminal unit 113 and thedisplay matrix 121. Further, FIGS. 5, 6, 7A, 7B, 8A and 8B show frontviews indicating a fabrication procedure of the light receiving region110, FIGS. 9, 10, 11 and 12 show front views indicating a fabricationstep of the display matrix 121 and FIGS. 13 and 14 show front viewsindicating a fabrication step of CMOS-TFTs arranged at the peripheralcircuits 112 and 122.

First, as shown by FIG. 3A, an underlying film 510 for preventingdiffusion of impurities from a substrate is formed on the entire face ofa glass substrate 500. A silicon oxide film is formed by a thickness of200 nm as the underlying film 510 by a plasma CVD (Chemical VaporDeposition) process.

Front views of the light receiving matrix 111 and the display matrix 121of FIG. 3A correspond to FIG. 5 and FIG. 9, respectively and the frontview of the CMOS-TFTs corresponds to FIG. 13. A sectional view takenalong a line A-A′ in FIG. 5 and a line B-B′ in FIG. 9 corresponds toFIG. 3A.

According to the embodiment, to fabricate a transmission type liquidcrystal panel, the substrate 500 may be a substrate for transmittingvisible light and a quartz substrate or the like can be used in place ofthe glass substrate 500. Further, according to the embodiment, TFTs arefabricated by a polycrystal silicon film and accordingly, a substratecapable of withstanding a process of forming the polycrystal siliconfilm is selected for the substrate 500. Mobility of the polycrystalsilicon film is very large and is about 10 through 200 cm²/Vsec and highspeed response can be carried out by constituting a channel formingregion of TFT by the polycrystal silicon which is particularly effectivein TFTs of the light receiving matrix 111 and CMOS-TFTs of theperipheral drive circuits 112 and 122.

Next, an amorphous silicon film is formed by a thickness of 55 nm by aplasma CVD process and excimer laser beam is irradiated so as tocrystallize. As a method of crystallizing an amorphous silicon film, athermal crystallizing process referred to as SPC, RTA process forirradiating infrared ray, a process using both of the thermalcrystallization and laser annealing and the like can be used.

Next, a crystallized silicon film is patterned in a land-like shape andactivation layers of TFTs 201 and 301 are formed. FIG. 13 shows theactivation layers 401 and 402. Next, a gate insulating film 520 coveringthe activation layers 201, 301, 401 and 402 is formed. The gateinsulating film 520 is formed by a thickness of 120 nm by a plasma CVDprocess by using raw natural gases of silane (SiH₄) and N₂O.

Next, a conductive film of a metal of Al, Cr, Mo or the like, aconductive polysilicon film or the like is formed and patterned by whichselect lines 202 and 302 and a gate electrode 403 are formed. Impuritiesproviding one conductivity are doped to the activation layers 201, 301,401 and 402 by using publicly-known CMOS technology with the wirings andthe electrode 202, 302 and 403 as masks by which source and drainregions are formed.

By doping phosphorus to the activation layers 201, 301 and 401, N-typesource regions 204 and 303, drain regions 203 and 304 and channelforming regions 205 and 305 are self-adjustingly formed. Illustration ofsource/drain regions of the activation layer 401 is omitted. Theactivation layers 201, 301 and 401 are covered with a resist mask andboron is doped only to the activation layer 402 by which a P-type sourceregion and a drain region and a channel forming region areself-adjustingly formed. After doping, doped impurities are activated.

Further, according to the embodiment, the activation layers 201, 301 and401 are of polycrystal silicon and accordingly, it is preferable tooptimize threshold values by adding P-type impurities of boron or thelike at least to regions for constituting the channel forming regions205 and 305 of the N-channel type TFT before forming the wirings and theelectrodes 202, 302 and 403.

Next, as shown by FIG. 3B, a first interlayer insulating film 530covering the entire face of the substrate 500 is formed. Contact holesreaching the source regions and the drain regions of respective TFTs anda contact hole reaching the gate electrode 403 of CMOS-TFT arerespectively formed in the interlayer insulating film 530. Thereafter, alaminated layer film comprising a titanium film, an aluminum film and atitanium film is formed and patterned by which a signal line 206, asource electrode 207 of the light receiving matrix 111 and a signal line306 and the drain electrode 307 of the display matrix 121 arerespectively formed.

Front views of the light receiving matrix 111 and the display matrix 121under the state correspond to FIG. 6 and FIG. 10, respectively. Asectional view taken along a line A-A′ and a line B-B′ in FIG. 6 andFIG. 10 corresponds to FIG. 3A.

Further, as shown by FIG. 14, CMOS-TFT is formed with an input wiring411 connected to the gate electrode 403, a wiring 412 connected to asource region of an n-channel type TFT, a wiring 413 connected to adrain region of a p-channel type TFT and a wiring 414 connected to adrain region of the n-channel type TFT and a source region of thep-channel type TFT.

As shown by FIG. 6, in the light receiving matrix 111, the select line202 is connected to a peripheral circuit 112V and is inputted with aselect signal for designating a light receiving pixel for reading signalelectric charge generated at the light receiving unit from theperipheral circuit 112V. Further, the signal line 206 is connected to aperipheral circuit 112H and read signal electric charge is outputted tothe peripheral circuit 112H via the signal line 206 and is outputted tooutside as image signal from the peripheral circuit 112H.

Further, the lead-out terminal unit 113 shown in FIG. 2 is formed with alead-out terminal 601. As shown by FIG. 6, the lead-out terminal 601 isformed in a shape of “L” along portions of the periphery of the lightreceiving matrix 111 where the peripheral drive circuits 112 are notconnected. Further, the lead-out terminal 601 is provided with a portionextended to outside of the light receiving region 110 and is connectedto a terminal formed in the outside lead-out terminal portion 130 at theportion.

Further, a terminal 602 for fixing potential of the electrode layer 308formed later at outside of the display matrix 121 is formed in thedisplay region 120.

After having been subjected to CMOS process mentioned above, the lightreceiving matrix 111 and the display matrix 121 both using polycrystalsilicon TFTs and CMOS-TFTs arranged to the drive circuits 112, 122 aresimultaneously completed. Although in this case, the TFTs are of aplaner type of top gate, they may be of a bottom gate type of inversestagger or the like. In this case, the order of forming the activationlayers 201, 301, 401 and 402 and the select lines 202 and 302 and thegate electrode 403 may be reversed and the gate insulating film 520 maybe formed after forming the select lines 202 and 302 and the gateelectrode 403. Further, LDD (Lightly Doped Drain) regions or offsetregions may be provided.

Next, as shown by FIG. 3C, a second interlayer insulating film 540 forseparating to insulate the light receiving unit TFT from the lightreceiving portion. A resin film canceling recesses and protrusions ofthe lower layer and providing a flat surface is preferable for thesecond interlayer insulating film 540. Polyimide, polyamide,polyimideamide or acrylic resin can be used for the resin film. Further,the surface layer of the second interlayer insulating film 540 may beconstituted by a resin film to provide a flat surface and the lowerlayer may be of a single layer or multi layers of inorganic insulatingmaterials of silicon oxide, silicon nitride, silicon oxynitride or thelike. According to the embodiment, a polyimide film is formed by athickness of 1.5 μm as the second interlayer insulating film 540.

Next, after respectively forming contact holes reaching the sourceelectrode 207, the drain electrode 307 and the terminals 601 and 602 inthe second interlayer insulating film 540, a conductive film 11comprising Ti, Cr, Mo, Al or the like constituting the lower electrodeof the light receiving unit and the electrode layer of the displaymatrix, are formed. According to the embodiment, the titanium film 11having a thickness of 200 nm is formed as the conductive film.

Next, an amorphous silicon film 12 of n-type for coupling thephotoelectric conversion layer and the lower electrode of the lightreceiving unit in ohmic coupling is formed over the entire face of thesubstrate by a thickness of 30 through 50 nm, in this case, 30 nm. Aresist mask 13 for patterning the titanium film 11 and the silicon film12 is formed.

By using the resist mask 13, as shown by FIG. 4A, the silicon film 12and the titanium film 11 are successively patterned. In this case, a dryetching process is used. As an etching gas of the silicon film 12, O₂gas mixed with CF₄ by 1 through 10% is used. In this embodiment, theconcentration of CF₄ is set to 5%. Further, as an etching gas of thetitanium film 11, a chlorine-base gas mixed with Cl₂/BCl₃/SiCl₄ is used.Further, the titanium film 11 is formed on the insulating film 540comprising resin and accordingly, it is necessary to select an etchinggas or an etchant of the titanium film 11 which does not convert theresin.

By patterning the titanium film 11, as shown by FIG. 4A, the lightreceiving matrix 111 is formed with the lower electrode 208 of the lightreceiving unit and the electrode layer 308 of the display matrix 121, anelectrode 309 for connecting with the pixel electrode and the terminal603 of the terminal unit 113, are formed. Layers 209, 310, 311 and 604which comprise the n-type silicon film 12 and are patterned in shapessubstantially the same as that of the titanium film 11, are formed onthe electrodes 208, 308, 309 and 603 comprising titanium.

The Layers 310, 311 and 604 other than those in the light receivingmatrix may not be formed since they are not provided with substantialfunction. In this case, patterning may be separately carried out inrespect of the titanium film 11 and the silicon film 12. However, thestep can be simplified by simultaneously carrying out patterning of thetitanium film 11 and the silicon film 12.

Further, as the layer 209 at the light receiving unit, microcrystalsilicon can be used in place of amorphous silicon. Further, siliconnitride, silicon oxide or silicon carbide added with an n-type impuritysuch as phosphorus or the like can be used.

FIG. 7A and FIG. 11 respectively show top views of the light receivingregion 110 and the display matrix 120. Further, in FIG. 7A and FIG. 11,the layers 209, 310, 311 and 604 are omitted.

As shown by FIG. 7A, the lower electrodes 208 are formed to separatefrom each other at the respective pixels in a lattice formed by theselect lines 202 and the signal lines 206. Further, the terminal 603connected to the lead-out terminal 601 is formed in the terminal unit113. The terminal 603 is formed in a shape of “L” along portions of theperiphery of the light receiving matrix which are not connected to theperipheral drive circuits 112 similar to the terminal 601. The sectionalview taken along a line A-A′ of FIG. 7A is illustrated by the lightreceiving matrix 111 of FIG. 4A.

As shown by FIG. 7B, the terminal 601 and the terminal 603 are connectedbetween upper and lower positions thereof via the plurality of contactholes formed in the insulating film 540. The smaller the contact, themore alleviated is antenna effect and accordingly, the terminals 601 and603 are connected by the plurality of contact holes 605. Further, asectional view taken along a line D-D′ of FIG. 7A corresponds to FIG.7B. The pitch of the contact holes 605 poses no problem in equalizingpotential of the upper electrode when it is at a degree the same as thatof the pitch of the light receiving pixels.

Meanwhile, as shown by FIG. 11, the display matrix 121 is integrallyformed with the electrode layer 308 in a lattice shape to cover theactivation layer 301 except portions in contact with the select lines302, the signal lines 306 and the electrodes 307. The electrode layer308 prevents light from being incident on the light receiving unit andprevents light from leaking from other than the effective displayregion. Further, the electrode layer 308 is connected to the lead-outwiring 602 at outside of the display matrix 121. Potential of thelead-out wiring 602 is fixed to constant potential and therefore,potential of the electrode layer 308 is also fixed to constantpotential. Thereby, potential of the pixel electrode at a layer abovethe electrode layer 308 can be prevented from varying by a variation inpotential of the select lines 302 and the signal lines 306 at a layerbelow the electrode layer 308.

Next, as shown by FIG. 4A, after patterning the titanium film 11 and thesilicon film, an intrinsic or a substantially intrinsic amorphoussilicon film 14 is formed by a film thickness of 1 through 2 μm, in thiscase, 1.5 μm, in continuation thereto, a p-type amorphous silicon film15 including boron is formed in a thickness of 30 through 100 nm, inthis case, a thickness of 50 nm. Further, a transparent conductive filmconstituting the upper electrode of the light receiving unit, in thiscase, an ITO (Indium Tin Oxide) film 16 is formed in a thickness of 120nm. Further, a resist mask 17 for patterning these films 14 through 16are formed.

Further, a state in which the amorphous silicon film 14 is substantiallyintrinsic designates a state in which a p-type impurity of boron or thelike is added by about 5×10¹⁶ through 1×10¹⁹ cm⁻³ and the Fermi level isdisposed at the center of the band gap. This does not mean that informing the amorphous silicon, the Fermi level is not necessarilydisposed at the center of the band gap and the Fermi level is deviatedslightly in a direction constituting n-type. Therefore, as describedabove, by adding the p-type impurity, the Fermi level can be disposed atthe center of the band gap. In this case, although the impurity isadded, the state where the Fermi level is disposed at the center of theband gap is referred to as a substantially intrinsic state.

Further, amorphous silicon germanium can be used in place of theintrinsic or the substantially intrinsic amorphous silicon film 14.Further, microcrystal silicon can be used in place of the p-typeamorphous silicon film 15.

Next, by using the resist mask 17, the ITO film 16, the p-type siliconfilms 15 and the intrinsic or the substantially intrinsic silicon film14 are successively patterned and as shown by FIG. 4B, the upperelectrode 212, the p layer 211 and the i layer 210 are respectivelyformed. In patterning the ITO film 16, the silicon films 15 and 14, RIE(Reactive Ion Etching) using an etching gas mixed with CF₄/SF₆/O₂ isused. Further, after patterning the ITO film 16, by using a gas etchingonly the silicon film, the silicon films 15 and 14 can be etched withthe upper electrode 212 as a mask and accordingly, the resist mask 17can be dispensed with. However, by leaving the resist mask 17 in etchingthe silicon films 15 and 14, the upper electrode 212 can be preventedfrom being converted by the RIE etching.

According to the embodiment, patterning steps of the silicon films 15and 14 and the ITO film 16 are carried out continuously, that is, nopatterning step is carried out during formation of the silicon film 15and 14 prior to formation of the ITO film by which lowering the aperturerate caused by a shift in patterns of the upper electrode 212 and thephotoelectric conversion layer 210 can be avoided.

Further, the upper electrode 212, the p layer 211 and the i layer 210are formed not only in the light receiving matrix 111 but also on theside of the terminal unit 113 by projecting them. This is for connectingthe upper electrode 212 to the electrode 604 at later steps withoutlowering the aperture ratio and considering fabrication margin orreliability of the light receiving unit, a width projected to the sideof the terminal unit 113 may be about 2 through 10 times as large as thepitch of the light receiving pixels.

Further, in view of the reliability of the light receiving unit, at thei layer 210, a boundary portion of the light receiving matrix 111 may beinsulated to prevent photo carriers generated at a portion of the ilayer 210 at outside of the light receiving matrix 111 from leaking intothe light receiving matrix 111. As one method of insulation, there is amethod in which a groove portion is formed in the i layer 210 along theboundary portion of the light receiving matrix 111 and an insulatingsubstance is embedded into the groove portion. The groove portion may beformed to completely divide the i layer 210. Further, when the boundaryportion is insulated as mentioned above, the steps of patterning thesilicon films 14 and 15 and the step of patterning the ITO film 16 needto carry out separately.

Next, after removing the resist mask 17, as shown by FIG. 1, the thirdinterlayer insulating film 550 constituting the matrix of the pixelelectrode 312 of the display matrix 121 is formed over the entire faceof the substrate 500. The insulating film 550 functions also as apassivation film of the light receiving matrix 111. As an insulatingfilm constituting the third interlayer insulating film 550, a resin filmof polyimide, polyamide, polyimideamide, acrylic resin or the like isformed to provide a flat surface. In this embodiment, a polyimide filmis formed with a film thickness at the light receiving matrix 111 of 0.3through 1 μm, in this case, 0.5 μm.

Next, contact holes reaching the upper electrode 212, the electrode 309and the terminal 603 are formed in the interlayer insulating film 550.In this case, an RIE etching process using O₂ gas mixed with 1 through10% of CF₄ as an etching gas is used. Although etching can be carriedout only with O₂ gas since the interlayer insulating film 550 comprisesresin, by mixing with CF₄, the layers 310 and 604 comprising n-typesilicon films on the electrode 309 and the terminal 603 are also etched.

After opening the contact holes, an ITO film having a thickness of 100through 300 nm, in this case, 120 nm is formed by a sputtering processand is patterned by using an etching gas mixed with CF₄/SF₆/O₂ by whichthe pixel electrode 312 connected to the electrode 309 and the lead-outterminal 606 for connecting the upper electrode 212 to the terminal 603are formed. FIG. 8A and FIG. 12 show respectively top views of the lightreceiving matrix 111 and the display matrix 121 under the state.

As shown by FIG. 8A, similar to the terminal 603, the lead-out terminal606 is formed in a shape of “L” to surround portions of the periphery ofthe light receiving matrix 111 to which the drive circuits 112 are notconnected. Further, the terminal 606 is connected to the upper electrode212 at outside of the light receiving matrix 111 and is connected to theterminal 603 at the terminal unit 113. According to the structure, byfixing the lead-out terminal 601 to constant potential, potential of theupper electrode 212 is fixed to constant potential via the terminals 606and 603. For example, to fix the terminal 601 at constant potential, theterminal 601 is connected to an outside lead-out terminal formed at thelead-out terminal unit 113 shown by FIG. 1. In this case, the outsidelead-out terminal can be formed by a conductive film the same as thoseof the signal lines 206 and 306 and the outside lead-out terminal andthe lead-out terminal 601 can integrally be formed.

Further, in order to render a total of the upper electrode 212 constantpotential, contact holes 607 for connecting the terminal 606 may beprovided with a pitch substantially the same as that of the lightreceiving pixels. Further, FIG. 8B shows a sectional view taken along aline D-D′ of FIG. 8A. Further, a sectional view taken along a line A-A′of FIG. 8A is illustrated by the light receiving matrix 111 of FIG. 1.

In this case, the terminals 601, 603 and 606 are formed to surroundportions of the periphery of the light receiving matrix 111 to which thedrive circuits 121 are not connected and accordingly, as is apparentfrom the constitution of section in FIG. 1, a side face of the lightreceiving unit (photodiode) is surrounded by the terminal 601, theterminals 603 and 606. In this case, potential of the terminal 601 andthe terminals 603 and 606 are fixed constant and accordingly, they canfunction as a shield against the light receiving unit. Therefore, evenwhen the display matrix 121 and the light receiving matrix 111 areprovided on the same substrate, the reliability of the light receivingunit can be maintained.

Further, other ends of the select lines 202 and the signal lines 206which are opposed to ends thereof connected to the peripheral circuits112H and 112V can also be protected electrically by the terminals 601,603 and 606 and accordingly, electrostatic breakdown of TFTs arranged atthe light receiving matrix 111 can be restrained.

On the other hand, according to the display matrix 121, as shown by FIG.12, the pixel electrodes 312 are formed such that they are electricallyseparated from each other at the respective display pixels andperipheries thereof overlap the electrode layer 308. By this structure,auxiliary capacity with the insulating film 550 as a dielectric body andthe electrode layer 308, the pixel electrode 312 as opposed electrodes,can be formed. Incidentally, in FIG. 12, the layer 309 on the electrodelayer 308 is omitted.

The embodiment is constituted by a laminated layer type forming thelight receiving unit (photodiode) on TFTs after fabricating the lightreceiving matrix 111 by TFTs and accordingly, even when the lightreceiving unit is formed by an amorphous silicon film as in theconventional case, light receiving TFT can be formed by polycrystalsilicon. Accordingly, an image sensor having excellent conversionefficiency and capable of responding at high speed can be fabricated onan insulating substrate such as a glass substrate or the like.

Further, by constituting the image sensor by a laminated layerstructure, the consistency with steps of fabricating a liquid crystalpanel which is conventionally constituted by polycrystal silicon TFT, isestablished. Accordingly, integration can be carried out on the samesubstrate without deteriorating the respective characteristics of theimage sensor and the liquid crystal panel.

Although according to the embodiment, the light receiving pixels arearranged two-dimensionally on the light receiving matrix 111, a linesensor in which light receiving pixels are arranged one-dimensionallymay be constituted. Further, when format of light receiving pixels aremade to be the same as format of a display unit, the light receivingpixels and the display pixels correspond to each other in one-to-onerelationship and accordingly, signal processing for displaying an imagedetected by the light receiving matrix 111 on the display matrix 121 canbe simplified and accelerated. Even in the case of a line sensor, anumber of light receiving pixels may be the same as a number of displaypixels in a row direction or a column direction.

When the pixel formats are made to coincide with each other, in the casewhere, for example, format of the display matrix 121 is 640×480 (VGAstandard), when one receiving pixel pitch is set to about 10 μm, anoccupied area of the light receiving matrix 111 is about 6.4 mm×4.8 mmand integration thereof to a liquid crystal panel is feasible.

Although according to the embodiment, the light receiving unit isconstituted by a photodiode of a resistor type and accordingly, then-type silicon layer 209 and the p-type silicon layer 211 for couplingthe lower electrode 208 and the upper electrode in ohmic coupling areprovided, for example, in the case of constituting a Schottky type, thelayer 209 and the layer 211 may be omitted.

Although according to the embodiment, a transmission type liquid crystaldisplay panel is constituted, the pixel electrode 312 can be rendered areflection type electrode having a mirror surface to constitute a liquidcrystal panel of a direct viewing type.

Although the embodiment is of a passive type provided with one TFTfunctioning as a switching element in the light receiving matrix 111 asa signal reading circuit connected to the light receiving unit(photodiode), an active type having an amplifying function can beconstituted by a plurality of TFTs.

Embodiment 2

The embodiment is a modified example of the terminal unit 113 in thelight receiving region 111. An explanation will be given of theembodiment in reference to FIG. 15.

According to the embodiment, the terminal 601 comprising a starting filmthe same as that of the signal line 306 is omitted. In this case, awiring 701 at the lowest layer is constituted by a wiring comprising astarting film the same as that of the electrode layer 308. The shape ofthe wiring 701 is made similar to that of the terminal 601 of the firstembodiment and may be extended to outside of the light receiving matrix111 to connect to a terminal formed at the outside lead-out terminalunit 130.

Embodiment 3

The embodiment is a modified example of the terminal unit 113 of thelight receiving region 111. An explanation will be given of theembodiment in reference to FIG. 16.

According to the embodiment, the terminal 601, 603 and the layer 604 areomitted. In this case, a wiring 801 arranged at the terminal unit 113 isconstituted by only a wiring comprising a starting film the same as thatof the pixel electrode 312. The shape of the wiring 801 is similar tothe terminal 601 of Embodiment 1 and the wiring 801 may be extended tooutside of the light receiving matrix 111 to connect to a terminalformed at the outside lead-out terminal unit 130.

Embodiment 4

The embodiment is a modified example of the terminal unit 113 of thelight receiving region 111. Although according to Embodiment 1, theterminal 601 at the lowest layer of the terminal unit and the sinal line306 are formed by the same starting film, they can be constituted by astarting film the same as that of the select line 302.

Embodiment 5

The embodiment is a modified example of the terminal unit 113 of thelight receiving region 111. In Embodiment 1, the terminal 603 comprisinga starting material the same as that of the electrode layer 308 isomitted and the terminal 606 and the terminal 601 are connected to eachother directly. Further, in this case, as described in Embodiment 4, theterminal 601 can be constituted by a starting film the same as thatof-the select line 302.

Embodiment 6

In this embodiment, an explanation will be given of a product to which aliquid crystal panel of an image sensor integrated type is applied.FIGS. 17A, 17B and 17C show schematic outlook views of electronicdevices according to the embodiment.

The liquid crystal panel according to Embodiment 1 is integrallyinstalled with the light receiving region having picture taking functionand the display region and accordingly, the liquid crystal panel isappropriate to a display unit having communication function of a TVconference system, a TV telephone, a terminal for internet, a personalcomputer or the like. For example, while looking at an image transmittedfrom a terminal of a dialogue partner by a display unit, an image of itsown is taken by a light receiving matrix and the image can betransmitted to the terminal of the dialogue partner and accordingly,bi-directional communication of dynamic image can be carried out.

Further, a notebook type personal computer 2000 having a liquid crystalpanel is illustrated in FIG. 17A as one of the electronic devices.Numeral 2001 designates a liquid crystal panel and numeral 2002designates an image sensor unit.

Further, as other electronic device, in FIG. 17B, a television telephone2010 is shown. Numeral 2011 designates a liquid crystal panel andnumeral 2012 designates an image sensor unit. A user can talk with adialogue partner while looking at an image thereof by the liquid crystalpanel 2011 and while taking an image of its own by the image sensor unit2012.

Further, FIG. 17C shows a portable type information terminal device 2020of a pen input type. Numeral 2021 designates a liquid crystal panel andnumeral 2022 designates an area sensor unit. Letter/graphic informationof a name card or the like is inputted by the area sensor 2022 and theinformation can be displayed on the liquid crystal panel 2021 orpreserved in the portable type information terminal device.

According to the present invention, the liquid crystal panel and thesensor unit are installed on the same substrate and accordingly, thedevice can be small-sized and light-weighted. Further, driving of thesensor unit can be made common to driving of the liquid crystal paneland accordingly, power conservation can be achieved. Therefore, as shownby FIGS. 17A, 17B and 17C, the present invention is preferably used inan electronic device of a battery drive type.

According to the embodiments, the display matrix and the light receivingmatrix are formed on the same substrate and accordingly, a film formingprocess and a patterning process can be made common in the respectivematrices by which the fabrication cost can be restrained low.

Further, according to the embodiment, the lead-out terminal for fixingpotential of the upper electrode of the light receiving unit is notintegrally formed with the upper electrode by which patternings of theupper electrode and the photoelectric conversion layer of the lightreceiving unit can be carried out continuously and lowering the apertureratio caused by shift of masks can be prevented. Further, by forming thelead-out terminal by a starting film the same as that of the pixelelectrode of the display matrix, the process can be simplified.

1-29. (canceled)
 30. An image sensor comprising: a thin film transistorin a pixel of a plurality of pixels; an insulating layer over the thinfilm transistor; a first electrode over the insulating layer; aphotoelectric conversion layer including a semiconductor film over thefirst electrode, the semiconductor film including amorphous silicon; anda second electrode over the photoelectric conversion layer, wherein aplurality of first electrodes including the first electrode areseparated from each other at respective of the pixels, and wherein thesecond electrode is common to the pixels.
 31. The image sensor accordingto claim 30, wherein the photoelectric conversion layer is patternedwith the second electrode as a mask.
 32. An image sensor comprising: athin film transistor in a pixel of a plurality of pixels; a firstinsulating layer over the thin film transistor; a first electrode overthe first insulating layer; a photoelectric conversion layer including asemiconductor film over the first electrode, the semiconductor filmincluding amorphous silicon; a second electrode over the photoelectricconversion layer; and a second insulating layer over the secondelectrode; a lead-out terminal over the second insulating layer, whereina plurality of first electrodes including the first electrode areseparated from each other at respective of the pixels, and wherein thesecond electrode is common to the pixels.
 33. The image sensor accordingto claim 32, wherein the photoelectric conversion layer is patternedwith the second electrode as a mask.
 34. An image sensor comprising: athin film transistor in a pixel of a plurality of pixels; an insulatinglayer over the thin film transistor; a first electrode over theinsulating layer; a photoelectric conversion layer including an n-typesilicon film over the first electrode, a semiconductor film over then-type silicon film and a p-type silicon film over the semiconductorfilm, the semiconductor film including amorphous silicon; and a secondelectrode over the photoelectric conversion layer, wherein a pluralityof first electrodes including the first electrode are separated fromeach other at respective of the pixels, and wherein the second electrodeis common to the pixels.
 35. The image sensor according to claim 34,wherein the photoelectric conversion layer is patterned with the secondelectrode as a mask.
 36. An image sensor comprising: a thin filmtransistor in a pixel of a plurality of pixels; a first insulating layerover the thin film transistor; a first electrode over the firstinsulating layer; a photoelectric conversion layer including an n-typesilicon film over the first electrode, a semiconductor film over then-type silicon film and a p-type silicon film over the semiconductorfilm, the semiconductor film including amorphous silicon; and a secondelectrode over the photoelectric conversion layer; and a secondinsulating layer over the second electrode; a lead-out terminal over thesecond insulating layer, wherein a plurality of first electrodesincluding the first electrode are separated from each other atrespective of the pixels, and wherein the second electrode is common tothe pixels.
 37. The image sensor according to claim 36, wherein thephotoelectric conversion layer is patterned with the second electrode asa mask.